Aging disrupts the coordination between mRNA and protein expression in mouse and human midbrain

Area of Science:

• Neuroscience
• Aging Research
• Molecular Biology

Background:

• Dopamine (DA) neuron loss is characteristic of Parkinson's disease.
• The impact of healthy aging on dopamine neurons is not fully understood.
• Investigating age-related changes in midbrain neurons is crucial for understanding neurodegenerative diseases.

Purpose of the Study:

• To determine if midbrain dopamine neurons degenerate during aging in mice and humans.
• To investigate age-related changes in gene expression within these neurons.
• To explore potential homeostatic mechanisms that maintain neuronal function during aging.

Main Methods:

• Comparative analysis of midbrain neuron numbers and gene expression (mRNA and protein) in aged vs. young mice and humans.
• Quantification of tyrosine hydroxylase (TH) and vesicular glutamate transporter 2 (VGLUT2) in midbrain and striatum.
• Analysis of ribosomal gene expression in dopamine neurons.

Main Results:

• No significant loss of midbrain neurons was observed in aged mice or humans.
• Age-related decreases in TH and VGLUT2 mRNA expression were found in both species.
• Striatal TH and VGLUT2 protein levels remained unchanged in mice, but terminal density decreased in humans, with unchanged protein expression in remaining terminals.

Conclusions:

• Aging induces species-conserved transcriptional changes in midbrain dopaminergic and glutamatergic neurons without significant cell death.
• Homeostatic mechanisms, including ribosomal translation, may compensate for age-related declines in transcriptional efficiency.
• Findings suggest potential therapeutic targets to maintain neurotransmission and enhance neuronal resilience during aging.